In the fabrication of semiconductor devices, it is known that damaging the substrate in an area surrounding the gate contact with implants of electrically inactive ions affects the electrical field along the surface of the substrate and, hence, the breakdown voltage of the device. See for example, U.S. Pat. No. 5,399,883, entitled "High Voltage Silicon Carbide MESFETS and Methods of Fabricating Same", issued Mar. 11, 1995. In all of these prior art devices, the damaged area extends at least from the gate electrode to the drain electrode, and in some devices the damage region also extends to the source electrode.
It is well known in the art that guard rings and the like can be diffused into the substrates of silicon semiconductor devices (and especially silicon power devices) for purposes of terminating or separating devices on a common substrate. However, devices formed on silicon carbide (SiC) substrates cannot be terminated using diffused guard rings because of the very small diffusion coefficients of conventional dopants in SiC. Use of field plates on SiC substrates is also limited since high electric fields in the dielectric and the subsequent breakdown of the dielectric is likely to occur before avalanche breakdown of the SiC.
However, all of these prior art devices, in actual practice, have relatively large reverse leakage current and a soft-breakdown. Accordingly, it would be highly advantageous to provide a method of fabricating semiconductor devices with an improved reverse breakdown characteristics.
It is a purpose of the present invention to provide a new and improved method of fabricating semiconductor devices.
It is another purpose of the present invention to provide a new and improved method of fabricating semiconductor devices including a Schottky diode or contact.
It is still another purpose of the present invention to provide a new and improved method of fabricating semiconductor devices including a Schottky diode or contact with improved reverse breakdown characteristics.
It is yet another purpose of the present invention to provide a new and improved method of fabricating semiconductor devices including a Schottky diode or contact on silicon carbide substrates with improved reverse breakdown characteristics.
It is a further purpose of the present invention to provide new and improved semiconductor devices including Schottky diodes or contacts.
It is still a further purpose of the present invention to provide new and improved semiconductor devices including Schottky diodes or contacts with improved reverse breakdown characteristics.
It is yet a further purpose of the present invention to provide new and improved semiconductor devices including Schottky diodes or contacts on silicon carbide substrates with improved reverse breakdown characteristics.